E7-12509. United States Section; Notice of Availability of a Draft Environmental Assessment and Finding of No Significant Impact for Improvements to the Donna-Brownsville Levee System, in the Lower Rio Grande Flood Control Project, Hidalgo and ...

AGENCY:

United States Section, International Boundary and Water Commission, United States and Mexico.

ACTION:

Notice of Availability of Draft Environmental Assessment (EA) and Draft Finding of No Significant Impact (FONSI).

SUMMARY:

Pursuant to Section 102(2)(c) of the National Environmental Policy Act (NEPA) of 1969, the Council on Environmental Quality Final Regulations (40 CFR Parts 1500 through 1508), and the United States Section, International Boundary and Water Commission's (USIBWC) Operational Procedures for Implementing Section 102 of NEPA, published in the Federal Register September 2, 1981, (46 FR 44083); the USIBWC hereby gives notice that the Draft Environmental Assessment and FONSI for Improvements to the Donna-Brownsville Levee System, in the Lower Rio Grande Flood Control Project, located in Hidalgo and Cameron Counties, Texas, are available. An environmental impact statement will not be prepared unless additional information which may affect this decision is brought to our attention within 30-days from the date of this Notice.

FOR FURTHER INFORMATION CONTACT:

Daniel Borunda, Environmental Protection Specialist, Environmental Management Division, United States Section, International Boundary and Water Commission; 4171 N. Mesa, C-100; El Paso, Texas 79902. Telephone: [phone]; e-mail: [e-mail].

DATES:

Comments on the Draft EA and Draft FONSI will be accepted within 30 days from the date of this Notice.

SUPPLEMENTARY INFORMATION:

Background

The USIBWC is authorized to construct, operate, and maintain any project or works projected by the United States of America on the Lower Rio Grande Flood Control Project (LRGFCP), as authorized by the Act of the 74th Congress, Sess. I Ch. 561 (H.R. 6453), approved August 19, 1935 (49 Stat. 660), and codified at 22 U.S.C. Section 277, 277a, 277b, 277c, and Acts amendatory thereof and supplementary thereto.

The LRGFCP was constructed to protect urban, suburban, and highly developed irrigated farmland along the Rio Grande delta in the United States and Mexico.

The USIBWC, in cooperation with the U.S. Fish and Wildlife Service (USFWS), prepared this Draft Environmental Assessment (Draft EA) for the proposed action of raising the Donna-Brownsville Levee System located in Hidalgo and Cameron Counties, Texas to improve flood control. This levee system is part of the LRGFCP that extends approximately 180 miles from the Town of Peñitas in south Texas to the Gulf of Mexico. The Donna-Brownsville Levee extends 65 miles along the Rio Grande, downstream from the Donna Pump Station in Hidalgo County to an area east of Brownsville, approximately 28 miles upstream of the Gulf of Mexico, in Cameron County.

Proposed Action

The Proposed Action would increase the flood containment capacity of the Donna-Brownsville Levee System by raising elevation of a number of levee segments to meet a 3-foot freeboard design criterion for flood protection. Height increases up to 2 feet are typically needed to reach the design freeboard value. The increase in levee height will result in an expansion to the levee footprint by lateral extension of the structure. Structural improvements may be required for some levee segments where seepage is a potential problem.

Alternatives to the Proposed Action

A No Action Alternative was evaluated for the Donna-Brownsville Levee System. This alternative will retain the existing configuration of the system, as designed over 30 years ago, and the current level of protection currently associated with this system. Under severe storm events, current containment capacity may be insufficient to fully control Rio Grande flooding, with risks to personal safety and potential property damage.

Summary of Findings

Pursuant to NEPA guidance (40 Code of Federal Regulations 1500-1508), The President's Council on Environmental Quality issued regulations for NEPA implementation, which included provisions for both the content and procedural aspects of the required Environmental Assessment. The USIBWC completed an EA of the potential environmental consequences of raising the Donna-Brownsville Levee System to meet current requirements for flood control. The EA, which supports this Finding of No Significant Impact, evaluated the Proposed Action and No Action Alternative.

Levee System Evaluation

No Action Alternative

The No Action Alternative was evaluated as the single alternative action to the Proposed Action. The No Action Alternative will retain the current configuration of the Donna-Brownsville Levee System, with no impacts to biological and cultural resources, land use, community resources, or environmental health issues. In terms of flood protection, however, current containment capacity under the No Action Alternative may be insufficient to fully control Rio Grande flooding under severe storm events, with associated risks to personal safety and property.

Proposed Action

Biological Resources

Improvements to the Donna-Brownsville Levee System require excavation and fill activities that would affect plant communities within the expanded levee footprint area. Nearly all vegetation removal, 51.5 acres, would be limited to invasive-species grassland that is expected to be rapidly re-established. While approximately 17 percent of the 65 mile levee system is adjacent to conservation areas, those non-native grasslands are located within the right-of-way (ROW) and have very limited value as wildlife habitat. No significant effects are anticipated for any of the 15 threatened and endangered species with potential habitat in the vicinity of the levee system. No wetlands are located within the potential levee expansion area.

Cultural Resources

Improvements to the Donna-Brownsville Levee System may adversely affect known archaeological resources, by mechanical excavation or by burial under the expanded levee footprint. Resources potentially affected include eight areas that may contain historic or prehistoric archaeological materials, and one known archaeological site. Out of 65 historic-age resources located in the levee system vicinity, twelve could be affected by the proposed levee improvements. Those historic-age resources are mostly associated with irrigation structures and canals adjacent to the levee system.

Water Resources

Improvements to the levee system would increase flood containment capacity to control the design flood event with a negligible increase in water surface elevation. Levee footprint expansion would not affect water bodies.

Land Use

The expansion would take place almost completely within the ROW and would not affect urban or agricultural lands. A minimum removal of woodland from natural resources management areas, less than 1 acre, would be required.

Community Resources

In terms of socioeconomic resources, the influx of federal funds into Hidalgo and Cameron Counties from the levee improvement project would have a positive local economic impact limited to the construction period; the impact would represent less than 1 percent of the annual county employment, income and sales values. No adverse impacts to disproportionately high minority and low-income populations were identified for construction activities. Moderate utilization of public roads is required during construction; a temporary increase in access road use would be required for equipment mobilization to staging areas.

Environmental Health Issues

Estimated air emissions of five criteria pollutants during construction represent from 0.06 percent to 1.64 percent of the Hidalgo and Cameron Counties annual emissions inventory. There would be a moderate increase in ambient noise levels due to excavation and fill activities. No long-term and regular exposure is expected above noise threshold values. A database search identified a number of waste storage or disposal sites in the levee system vicinity, all located within the City of Brownville. None of those sites would affect, or be affected, by the levee improvement project.

Best Management Practices and Mitigation

Engineering design measures will be used, including optimization of the levee expansion alignment to avoid impacts on wooded vegetation, wetlands, and other natural resources. Best management practices during construction will include development of a storm water pollution prevention plan to avoid impacts to receiving waters, and use of sediment barriers and soil wetting to minimize erosion.

To protect vegetation, the construction corridor may be re-vegetated with herbaceous or woody vegetation, as agreed with the natural resources management organization where the levee expansion corridor is located. To protect wildlife, construction activities will be scheduled to occur, to the extent possible, outside the March to August bird migratory season.

To avoid significant impacts on cultural resources, an additional survey of archaeological and historical resources will be conducted following completion of the engineering design phase, and mitigation actions will be adopted as recommended by the Texas Historical Commission (THC). Measures to avoid or minimize potential impacts to historical or archaeological resources will be specified in a Memorandum of Agreement between THC and the USIBWC.

Availability

Single hard copies of the Draft Environmental Assessment and Finding of No Significant Impact may be obtained by request at the above address. Electronic copies may also be obtained from the USIBWC Home Page at http://www.ibwc.state.gov.

Dated: June 25, 2007.

Susan Daniel,

General Counsel.